Screw-grinding machine



W. WEND TLAND.

SCREW GRINDING MACHINEL APPLICATION FILED SEPT-19,19l8.

Patented Jan. 20, 1920.

2 SHEETSSHEET I.

' W. WENDTLAND.

SCREW GRINDING MACHINE:

APPLICATION FILED SEPT. 19. I918.

Patented Jan. 20, 1920.

2 SHEETS-SHEET 2.

WILLIAM WENDTLAND, OF NEW YORK, N. Y.

SCREW-GRIN DING MACHINE.

Specification of Letters Patent.

Patented Jan. 20, 1920.

Application filed September 19, 1918. Serial No. 254,725.

To all whom it may concern:

Be it known that I, WILLIAM WENDTLAND, a citizen of the United States, residing in the city of New York, borough of Manhattan, county and State of New York, have invented a certain new and useful Screw- Grinding Machine, of which the following is a specification.

The main object of the invention is to provide a suitable screw grinding machine which will grind a true thread in a blank even though there be irregularities or inaccuracies in the pitch of the master screw. With this object in view, the invention embodies compensating means for obviating inaccuracies in the master screw and an improvement in the tail stock where it automatically follows up the blank being operated upon.

Features of the invention other than those specified will be apparent from the hereinafter detailed description taken in conjunction with the accompanying drawings.

In the accompanying drawings, I have illustrated one practical form of the invention, but the construction shown therein is to be understood as illustrative, only, and not as defining the limits of the invention.

Figure 1 is a side elevation. of the screw grinding machine;

Fig. 2 is a sectional view taken through the tail stock;

Fig. 3 is a' sectional view taken through a modified form of tail stock;

Fig. 4 is a plan view of the master screw and connected parts;

Fig. 5 is a side elevation of the parts shown in Fig. 4; and

Fig. 6 is a sectional view, somewhat enlarged, taken on the line 66 of Fig. 4, looking in the direction of the arrows.

The machine 1 embodies a bed 2 mounted on a table 3 by means of suitable supports 4, and this bed carries a head stock 5, a tail stock 6 and intermediate grinding mechanism 7.

Power to run the machine is derived through a main shaft 8 which may be placed, in any convenient location, as under the table 3, where it is mounted in suitable brackets 9 and it is provided with two fixed pulleys 10 and 11, one for direct and the other for reverse motion. The head stock 5 has two standards 12 which extend upward from bed 2 and at their upper ends carry a shaft 13 provided with a suitable clutch mechanism 14 which can be thrown lnto engagement with either of two pulleys l5 and 16, both of which normally run idle on the shaft 13. The clutch mechanism 14 is shifted by means of a lever 17 fulcrumed on a bracket 18 that rises from the bed 2 and the lower end of said lever 17 is provided with a handle 19, extending to a convenient location so that the clutch may be readily manipulated. The pulleys l0 and 15 are connected by a direct belt 20 and the pulleys 11 and 16 by a cross belt 21 so that when the clutch 14 is brought into engagement with the pulley 15, the shaft 13 is driven in one direction and when the clutch is brought into engagement with the pulley 16, it is driven in the reverse direction. When the clutch is disengaged from both pulleys, the shaft is at rest.

Shaft 13 is provided with a suitable face plate 22 from which extends a rod 23 which is fixed therein and mounted so as to slide without lost motion in a groove in a disk 24, fixed to the master screw 25, in any suitable manner. The master screw turns in a nut 26 which is mounted so that it may be either fixed or turned in a bearing 27 that rises from the bed 2. Master screw 25 has one end plane so as to form a shaft 28 which turns freely and may be shifted in the direction of its length in a suitable bearing 29, which also rises from the bed 2 in a manner which corresponds with the bearing 27. Bearings 27 and 29 are each provided with suitable brackets 30 and 31, respectively, to receive a sliding shaft 32 which slides freely therein, but does not turn because the bracket 30 is slotted to receive a cam 33 which slides in the slot of the bracket 30 and fits snug and is fixed in a slot 34 of the shaft 32. Cam 33 engages an arm 35 which is fixed to the nut 26, and preferably integral therewith, and is held in engagement with the cam by means of a suitable coil spring 36 which runs to a small bracket 37 that projects from the pedestal 27. It is here noted that the cam 33 is shifted according to irregularities in the master screw 25. If this screw is absolutely uniform and correct throughout, the upper surface of the cam 33 is horizontal and smooth. If the pitch of the master thread 25 changes, one way or the other, this cam 33 is inclined to correspond, and if the thread is irregular, the cam 33 is given corresponding irregularities so that under the tension of the to be described, the nut 26 isslightly turned one way or the other and the screw 25 is given a corresponding movement, as will be described more in detail.

The shaft 32 has longitudinal motion imparted to it by a bracket 38 which is fixed to the shaft and also mad to fiton the smooth part 28 of the screw 25 and between collars 29 which are fixed to this screw shaft so that as the screw shifts, the shaft 32 shifts also and in the same direction, but it has no motion in the screw shaft 25 except in the direction of the motion of its length. From the. foregoing it is apparent that when the cam 33 is made so as to compensate for any irregularities in the master screw 25, the turning of the nut 26 one way or the other will cause the longitudinal movement of the screw shaft 26 to be uniformand accurate at all times'so that a correct.

movement will be given to the blank which is being ground in a manner which will now be described.

The screw shaft 25 at its end remote from the disk 24 is provided with a face plate 40 and a center 41'. .The face plate 40 is recessed so as to receive a suitable dog 42 on a blank 43 which is having its screw threads made true by a grinding wheel 44 which is mounted in any suitable way and driven froman desired source of power as a pulley 45 with belt 46. The grinding wheel is mounted so that it may be brought 'to or from the blank. The other end of the blank 43, that is the end remote from the center 41, is placed on another center 47 of the tail stock 6 and this center is put in spindle 48 which slides freely in the base 48 which rises from the" table 2. Obviously, some means must be' provided to keep the center 47 in proper relation to the blank 43. This may be done as shown in Fig. 2 where the spindle 48 is recessed or slotted at its lower end to' receive a cord 50 which runs over a suitable pulley 51 and the cord is 1 connected to a, weight 52' so that the center lar 53 47 is properly pressed against the screw. If the base 49 of the tail stock 6 be made as shown in Fig. 3, the spindle 48 has a collar 53 in a chamber 54 and a coil spring 55 is provided which rests against this -coland against one end of the chamber 54, and so forces the spindle 48 against. the blank 43. In any event, the blank is held so that the spindle 47 will have a longitudinal movement which is exactly the same as i the longitudinal movement of the screw 25 and the blank willrun freely between centers and be ground by a rotary, but otherwise fixed grinder and be ground absolutely true because of the cam 33 even though there be irregular threads in the master screw 25. If for any reason, it is desired to inaaaee reproduce the irregularities in the master thread 25, it is obvious that this may .be done by letting the cam 33 be plain and horizontal. r

In view of the foregoing description, the operation of the machine will be readily understood. Assuming the parts to be in the position indicated inyFig. 2, and power applied both to the grinding wheel and to the screw 25, the thread in the blank is properly ground, itbeing understood that the grinding wheel 44 is so mounted that it may be brought to or away from the blank so as to alwa s be in proper relation thereto when grin ing. The blank is inserted or removed from the machine in the usual manner and the grinding wheel is brought up or removed from the blank in the conventional way. It will be noted that when grinding the wheel rotates and has no other movement, and the blank is fed so that the thread properly engages the wheel because of the dual movement of the blank both about its axis and in the direction of its length. Because of the reversing clutch 14 the blank may be ground both ways.

While I have shown and described one embodiment of my invention, it is to be un-.

benter to receive one end of the blank mounted in a spindle of the tail stock, means for mounting the spindleso that it can slide in the tail stock and means for causing the center of the spindle of. the tail stock to properly engage the blank at all times regardless of the position in which the blank places the spindle through the action of the master screw.

2. In a machine of the class described, a bed supporting a head stock, a tail stock and uprights adapted to support a master screw, a master screw mounted in said supports, and a shaft parallel with said master screw and means for mounting the same so that it can slide in the direction of its length and not move otherwise, means for connecting said shaft with said screw so that both have the same longitudinal movement, a nut mounted so as to turn on said screw, a cam fixed to said shaft, a projection from said nut resting on said cam and means for keeping the two in contact, the cam being so shaped and disposed as to compensate for any irregularities in the threads of the master-screw.-

3. In a machine of the class described, a bed supporting a head stock, a tail stock and two supports adapted to carry a master 'screw, a master screw mounted in said sup- 5 ports, a face late associated with said screw and provide with a groove, a rotary spin dle in said head stock, means for causing the rotary spindle to be driven in either of two directions or kept from movement, a face plate slidably engaging the groove in the face associated with the master screw,- a center on said master screw, a center on the tail stock, means for causing the center n the tail stock to be in proper enga ement with the blank at all times when t e machine is in operation, and means for permitting the center of the tail stock to move in the direction of its length in accordance with the pressure applied by the blank while under the influence of the master screw.

In testimony whereof, I have signed my name to this specification.

I 'WILLIAM. WEN DTLAN D. 

